Vtec Can't On

[gerek]

I'M NEWLY USED SR4 BODY WITH B16A ENGINE....LAST FEW DAY I ALREADY REPLACE GASKET COZ HAD LEAKING . BUT NOW I GOT ANOTHER PROBLEM ....VTEC CAN'T ON...WHY.....HOPELY ALL MEMBERS WILL HELP ME MEKACHIH.... :unsure:

 

[hattech-v]

ur check engine light on or not?

 

[SePaT]

check your vtec solenoid ..

 

[hattech-v]

yeap... maybe the magnet kong edi...

 

[Riezal-R]

Kalau ada check light, use it wisely. It helps a lot. And just saying VTEC can't open is too subjective. So many possibilities.

 

[lan evo]

check ur solenoid socket

 

[sakuraguy]

http://cayotic.com/b16a_camshaft.jpg

These are camshafts. There are three cam lobes, which are the triangle type lumps in groups of three along the shaft. The thinner, shortest one is the primary lobe. The wider, medium high lobe is the secondary. The middle lobe (widest and biggest) is the VTEC lobe.

Now, when your engine is running, these shafts are spinning. In this picture, you can see the engine head. Its off of a b18c1 (gs-r)

http://cayotic.com/diagram.jpg

you can plainly see from left to right on the first group of cam lobes, Primary, VTEC, and Secondary(circled in red). The valves are under the two little flathead screws that are near the walls (circled in yellow) Under each cam lobe, you can see three things that resemble blocks. Those are the rocker arms (circled in green)

http://cayotic.com/coveroff.jpg

The way the engine works is that the camshaft spins, and the lobes hit the rocker arms. the valves are connected to the rocker arms. so when the lobe hits, rocker arm is pushed down, and the other end that is attached to the valve is raised, therefore raising the valve. In this case the closer camshaft is the exhaust camshaft, so therefore the exhaust valves would be opened by the rocker arms.

How does vtec work then? You can see that there is no valve under the VTEC rocker arm for the rocker arm to act upon. So when you are not in VTEC, the primary and secondary lobes are hitting the rocker arms, and the valves are working. But the VTEC rocker arm is just moving along, being pushed down by the VTEC lobe, but its not acting on anything.

For VTEC to kick in, you need 2 things. 1) Engine must be in normal operating temperature - read: If you just turned on the car for the first time that day, vtec is not going to kick in. 2) Oil pressure must be up to par - read: if your oil pump is malfunctioning, or you have a low oil level, VTEC will not engage.

Now, on this picture, the VTEC solenoid is circled below.
http://cayotic.com/vtecsolenoid.jpg

What that solenoid does is when oil and temp is optimal, it sends a pin thru each set of rocker arms. U can't see it in the pictures, but a pin slides thru a hole in each rocker arm, effectively linking all the rocker arms to move in unison.

 

[prozac]

Nice VTEC tutorial.

 

[waw_8921]

I'M NEWLY USED SR4 BODY WITH B16A ENGINE....LAST FEW DAY I ALREADY REPLACE GASKET COZ HAD LEAKING . BUT NOW I GOT ANOTHER PROBLEM ....VTEC CAN'T ON...WHY.....HOPELY ALL MEMBERS WILL HELP ME MEKACHIH.... :unsure:

:D gerek...gerek...semlm kete kou temp problem, ni vtec can't on lak....ok la,
I suggest u try checkout ur vtec sensor....(problem betul kete mamat nie..)

 

[Civic-R]

Is it you not yet fully warm up the car.Cold engine can't start vtec one.Haf to wait until temperature normal.

 

[zero4]

aiks, who say cold engine cannot on vtec, really meh?

 

[Sato]

Did u change the engine oil also ???

If engine oil viscocity too high...let say 15w-50w......vtec will not on...hahaha....

I've tried it once.....shell helix ultra.......not recommended for vtec !

 

[SePaT]

Did u change the engine oil also ???

If engine oil viscocity too high...let say 15w-50w......vtec will not on...hahaha....

I've tried it once.....shell helix ultra.......not recommended for vtec !

i dont think so.. many vtec drivers here use helix ultra... never encountered such thing before..

 

[Civic-R]

I experienced it yesterday.From my knowledge,even b16a oso got this problem can't engaged vtec when engine is still cold.Zero4,any ideas?

 

[Sato]

I'm not too sure about it !

I encountered it b4.....mine is CF4 SIR.....so....change to shell helix ultra......rev over 6000rpm still no vtec.....terrible.....

After that...change back to petronas 0w-30w, straight away 5500rpm vtec on !

I asked several honda service centres, they all not recommend viscocity like 15w-50w or 60w

 

[SiRCRX]

Standard ECU takes into account temp for VTEC activation. When it's not reaching the pre-set value yet, VTEC wont on. Doesn't matter what oil you use.

 

[waw_8921]

gerekk vtec can't on....

Standard ECU takes into account temp for VTEC activation. When it's not reaching the pre-set value yet, VTEC wont on. Doesn't matter what oil you use.

:) right....that was my experience too.Not only vtec la,any car also just let the engine running first as a warm-up...
even u want to play any games,warm-up first..baru betoi.. :D

 

[SiGNAL]

sakuraguy,

I think you should give credit to the author. Not just stealing it.


My friend last time set his VAFC too rich till the vtec wouldn't engage... lol